A sales rep who died after decades of driving with his windows open may have been killed by car fumes.

Health-conscious John Moreton, 58, did not smoke and rarely drank. Out of the blue he was struck down with a lung condition thought of as an industrial disease.

Medics who diagnosed interstitial pneumonitis later told John's family he had the lungs of someone who smoked 40 cigarettes a day.

Yesterday his widow Maureen said: "The doctors kept asking if he'd worked with dangerous chemicals but he'd spent his life in office blocks or meeting clients.

"He had never been exposed to asbestos, worked in mining or spray painting."

But John had driven thousands of miles a year to and from work and meeting customers of his employers Cadbury - and it could have caused his death.

His family said doctors told them there are increasing numbers of people with no history of asbestos exposure who develop lung disease triggered by pollution.

Maureen, 56, said: "It is terrifying that millions are being slowly killed by traffic fumes. There must be new laws to cut down on pollution because it is killing people."

Maureen added: "John drove about 30,000 miles every year, almost always with his window down. The cars had air conditioning but he didn't like it. He found it too dry.

"Even in the winter he would wind the window down a couple of inches and in the summer he had it right down all the time."

For 33 years John made a round trip of 60 miles from his home in Coventry to Cadbury's HQ in Bournville, Birmingham. He also travelled for up to five hours a day on the motorway to see clients.

John spent his final months at home needing oxygen to help him breathe and died on December 28. He leaves a son Paul, 30, an events manager, daughter Charlotte, 22, a teacher, and two grandchildren. Respiratory expert Prof Simon Johnson, of the University of Nottingham, said: "Car fumes can contribute to diseases. It may be true that consistent exposure to fumes caused this disease but without an in-depth study it cannot be scientifically certified."

University Hospitals Coventry and Warwickshire NHS Trust, which treated John, said: "Any relationship to traffic fumes must be purely speculative."